System Builder - software to learn objects while building your own systems (virtual worlds). You construct a virtual world on the display from visual objects: trees, houses, cars, dogs and so on. They can move, change their images and interact according to the laws your set. You may even try to create a simple game episode using 'SB'. 'SB' will help you to get some skills of working in object media. Don't be afraid to try - software is easy enough in control and doesn't need any special knowledge. It has traditional Windows interface, powerful help system and several detailed samples. Was presented in ZDNet Software Library before.